Ms Hamilton returned to Canberra last year after spending 22 years in Sydney. Between 2004 and 2008 she was a Greens councillor on Leichhardt council.

ACT Greens convener Simon Copland said at the time Ms Hamilton's actions were against party process, which prohibits preselection candidates from campaigning against each other in the media. He said the party would take ''appropriate action''.

Ms Hamilton said on Sunday her assumptions were based on the activities in major parties.

Asked if she still had a problem with Mr Sheikh's nomination, she said: ''The Greens are a broad church, an ecumenical collection of people from across Australia.''

Pressed on the issue, she said: ''I know what the question was, that was my answer.''

Asked if the party had taken action against her, she said: ''There were words about that … I don't think I've been silenced.''

On her candidate statement, which went to the 600 ACT Greens members, she points out she grew up in Canberra.

The new ACT Greens convener Clare Quinn said on Sunday the party was considering whether Ms Hamilton had breached party rules.

''There is certainly a view that that has occurred but the party hasn't investigated that fully,'' she said.

Mr Sheikh resigned from the GetUp! advocacy group earlier this year before moving to Canberra, where his wife has taken a job at Australian National University.

He joined the Greens several months ago and denied he was a blow-in for the ACT Senate preselection.

''We're here for the long haul. We've made a permanent move here because it's a perfect place to raise a family,'' he said.

He is confident the Greens can unseat Senator Humphries through a campaign based on Opposition Leader Tony Abbott's plan to cut the public service nationwide by 12,000 jobs through natural attrition.

''The other side here wants to trash Canberra's economy and we saw that happen in '96-97,'' Mr Sheikh said. ''At the Tuggeranong community festival on Saturday, I engaged with people who are deeply concerned about what Tony Abbott will do to our community.''